Succinic acid, meso-dimethoxy

They then prepared the completely methylated derivatives of adeno-gine . and guanosine by simultaneous deacetylation and methylation of the acetylated nucleosides. In this way, trimethyl-iV-methyl adenosine and trimethyl-A -methyl guanosine were formed, and isolated as the hydrochlorides. On hydrolysis of the adenosine derivative by means of dilute hydrochloric acid, 6-iV-methyladenine and trimethyl-D-ribo-furanose were isolated. The same trimethyl sugar was isolated from the methylated guanosine and was identified in each case by oxidation, first to trimethyl-7-D-ribonolactone and then to meso-dimethoxy succinic acid. It follows that the sugar component has the furanose ring-structure. 

The ring structure of the ribose residue was ascertained" in the same general manner as for adenosine and guanosine. Triacetyl-dihydrouridine was prepared by the hydrogenation of triacetyl-uridine. On simultaneous deacetylation and methylation this was transformed to the fully methylated dihydro-uridine. By simultaneous hydrolysis and oxidation of this product, with hydrobromic acid and bromine, trimethyl -D-ribonolactone was formed, its identity being confirmed by oxidation to meso-dimethoxy-succinic acid. It follows that the ribose component has the furanose ring structure, and that uridine is 3 -D-ribofuranosyl-uracil. 

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